Preliminary X-ray crystallographic study of adenylosuccinate synthetase from Escherichia coli.

Adenylosuccinate synthetase, a dimeric enzyme of 96,000 Mr, catalyzes the first committed step toward the de novo biosynthesis of AMP. Large, single crystals of adenylosuccinate synthetase from Escherichia coli grow from solutions of polyethylene glycol and ammonium sulfate. Crystals from ammonium sulfate belong to the orthorhombic space group P212121 with unit cell parameters a = 79.0 A, b = 70.2 A and c = 152.6 A. Crystals from polyethylene glycol belong to the space group P21, having unit cell parameters of a = 71.16 A, b = 71.99 A, c = 82.95 A, and beta = 71.52 degrees. The asymmetric units of both crystal forms probably contain the entire dimeric enzyme.